Dawn: fix rendering to mipmapped textures.

Use a texture view with a mipLevelCount of 1 when using a texture
as an attachment.
Dawn validation will fail if the view has more than one mip.

Change-Id: I6a3594dade9f65fa8e713d433797414c6ba8ecec
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/249423
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>
1 file changed